Distribution of tetracycline resistance genes tet(M), tet(O), tet(L) and tet(K) in blood isolates of viridans group streptococci harbouring erm(B) and mef(A) genes. Susceptibility to quinupristin/dalfopristin and linezolid

Susceptibility to erythromycin, tetracycline, clindamycin, quinupristin/dalfopristin and linezolid was investigated using 111 consecutive non-duplicate blood culture isolates of viridans-group streptococci (VGS). The erm(B) and mef(A) genes were detected, either alone or in combination, in the 47 (42%) erythromycin-resistant strains. The tet(M) gene alone was predominant (78%) in the 36 (35%) tetracycline-resistant isolates. Two isolates carried the tet(O) gene alone and two others the tet(L) associated with tet(O) or tet(M). The association between erythromycin and tetracycline resistance was common and the erm(B) and tet(M) determinants seem to be associated in our VGS. We found three isolates resistant to quinupristin/dalfopristin, all of them were erythromycin and tetracycline-resistant. For all isolates tested, linezolid MICs were ≤2 mg/l.     

Molecular characterisation of Hungarian macrolide-resistant Streptococcus pneumoniae isolates, including three highly resistant strains with the mef gene

The macrolide resistance of 304 Hungarian Streptococcus pneumoniae isolates was investigated. Antibiotic sensitivity testing was performed in air and in 5% CO₂. More erythromycin resistance was noted when growth was in CO₂. A resistance determinant was found in almost all isolates: erm(B) gene (87.4%), mef genes (9.2%) and one strain with the erm(TR) gene. This indicates that screening for carriage of resistance determinants should always be done in the presence of 5% CO₂. We found three isolates with mef(E), which were highly resistant to erythromycin. These contained multiple and some novel, ribosomal mutations. The most prevalent serogroups were 6, 19 and 14. Based on the PFGE pattern, we found identity between the Hungarian isolates and two PMEN clones.     

Antibacterial resistance patterns in Streptococcus pneumoniae isolated from elderly patients: PROTEKT years 1-5 (1999-2004)

The antibacterial susceptibilities of 6646 Streptococcus pneumoniae isolates collected in 38 countries from patients ≥65 years of age with community-acquired respiratory tract infections (RTIs) during years 1–5 of the PROTEKT study (1999–2004) were analysed. Rates of erythromycin resistance (36.0%), penicillin non-susceptibility (31.3%; 20.2% resistant plus 11.1% intermediately susceptible) and resistance to multiple antibacterials (37.2%) were stable over the 5 years. The most common macrolide resistance mechanism was erm(B) (61.4%); erm(B) + mef(A) strains increased from 5.4% (year 1) to 7.4% (year 5) (P = 0.037). Overall, 37.2% of isolates exhibited resistance to two or more antibacterials, including 15.9% resistant to both penicillin and erythromycin. Antibacterial resistance was highest in the Far East. Telithromycin resistance was rare (0.12%). Appropriate alternative empirical first-line therapies may be required for treating community-acquired RTIs in the elderly.     

Resistance to macrolides in Group A streptococci from the European section of Turkey: genetic and phenotypic characterization

The aim of this study was to determine the susceptibilities to macrolides of Group A streptococcal isolates from the European section of Turkey. In the case of resistant isolates, the patterns and genetic mechanisms of erythromycin resistance were studied. Seven (2.7%) of the 260 isolates were resistant to erythromycin. Four of them showed the M phenotype and harboured mefA genes whereas three isolates showed the inducible macrolide, lincosamide and streptogramin B resistance phenotype and harboured ermTR genes. In the European section of Turkey, the current resistance rate of Group A streptococci to macrolides remains low.     

Prevalence and characterization of the mechanisms of macrolide, lincosamide and streptogramin resistance in viridans group streptococci

The presence of erm genes conferring constitutive and inducible resistance, as well as that of the mefA gene conferring only constitutive resistance, was investigated using PCR in 70 erythromycin resistant (MIC≥1 mg/l) strains of viridans group streptococci (VGS) (18 Streptococcus mitis biotype 1, 16 S. mitis biotype 2, 15 S. oralis, 12 S. salivarius and nine S. sanguis) isolated from the oropharynx of healthy Greek children. All of the 56 isolates belonging to resistance phenotype M harbored the mefA gene. All of the 14 isolates constitutively resistant to macrolides and lincosamides (phenotype CR) harbored the ermB gene. Co-presence of both genes was not observed, whereas class A erm gene (previously known as ermTR) was not detected. Our results are consistent with a possible role of VGS as a reservoir of resistance genes now prevalent in pathogenic species of streptococci.     

Macrolide resistance phenotypes in Streptococcus pneumoniae in Santiago,Chile

The mechanism of resistance was investigated in 39 macrolide-resistant clinical isolates of Streptococcus pneumoniae isolated from January 1997 to July 1999 in Santiago, Chile. Our results showed that 22 (56.5%) were macrolide-resistant, clindamycin-susceptible isolates (M phenotype) and 17 (43.5%) were macrolide and clindamycin resistant (MLS(B) phenotype). mefE gene was detected in all M phenotype, while ermB gene was detected in all MLS(B)-phenotype strains. Serotype 14 was the most frequent serotype among M-phenotype strains, and serotypes 19 and 23F were the most frequent serotypes in MLS(B) strains. These results demonstrate that both phenotypes of macrolide-resistant S. pneumoniae are found in Santiago, Chile, with the M phenotype predominating.     

Macrolide resistance phenotypes and mechanisms of resistance in Streptococcus pyogenes in La Rioja, Spain

One hundred and thirty seven consecutive clinical Streptococcus pyogenes isolates were evaluated for macrolide-lincosamide-streptogramin resistance (MLS). Forty of these isolates were resistant to erythromycin (29.2%), 36 of them showed the new M resistance phenotype (erythromycin resistant and clindamycin susceptible) and four isolates had the MLS(B) resistance phenotype (erythromycin and clindamycin resistant). In all 36 isolates with the M resistance phenotype, the mef gene was identified by polymerase chain reaction (PCR). In two of the four S. pyogenes isolates with the MLS(B) phenotype, both ermB and ermTR genes were found; negative results were obtained with the other two isolates which might possess a new mechanism of high level resistance against erythromycin not previously described. In summary, a high rate of erythromycin resistance was found in S. pyogenes isolates and the active efflux pump mediated by the mef gene was the mechanism most frequently involved.     

2016年福建省晋江市医院细菌耐药性监测

目的 了解福建省晋江市医院2016年临床分离菌对常用抗菌药物的敏感性和耐药性。方法 收集本院2016年1-12月的临床分离菌株,采用自动化仪器法或纸片扩散法(K-B法)进行细菌药物敏感性试验,按美国临床实验室标准化研究协会(CLSI)2016年版标准判断结果,WHONET 5.6软件统计分析。结果 共分离临床菌1,744株,其中革兰阳性菌590株,占33.8%,革兰阴性菌1,154株,占66.2%。金黄色葡萄球菌和凝固酶阴性葡萄球菌中甲氧西林耐药株(MRSA和MRCNS)检出率分别为29.6%和72.9%,MRSA和MRCNS对常用抗菌药物的耐药率均显著高于甲氧西林敏感株(MSSA和MSCNS),未发现替考拉宁、万古霉素和利奈唑胺耐药株。肠球菌属中粪肠球菌对多数测试抗菌药物(利奈唑胺除外)的耐药率均显著低于屎肠球菌,发现利奈唑胺耐药粪肠球菌2株,未发现替考拉宁和万古霉素耐药的粪肠球菌和屎肠球菌。肺炎链球菌非脑膜炎分离株对青霉素均高度敏感。大肠埃希菌、克雷伯菌属(肺炎克雷伯菌和产酸克雷伯菌)、奇异变形菌中ESBLs检出率分别为50.4%、22.5%和16.7%,肠杆菌科细菌对碳青霉烯类抗生素高度敏感,但有2.8%的肺炎克雷伯菌对碳青霉烯类耐药。铜绿假单胞菌对亚胺培南和美罗培南的耐药率分别为29.7%和21.2%。不动杆菌属(鲍曼不动杆菌占94.2%)对亚胺培南和美罗培南的耐药率分别为60.5%和62.9%。流感嗜血菌和卡他莫拉菌β-内酰胺酶产酶率分别为46.9%和99.3%。结论 县级医院临床分离菌的构成和耐药性均有别于大型综合性医院。     

The prevalence of antimicrobial resistance among uropathogens causing acute uncomplicated cystitis in young women

Four hundred and fifty-two urine isolates from women with acute uncomplicated cystitis and a positive urine culture presenting to a sexually transmitted disease clinic were collected during 1989–1991, and 213 specimens were collected over 1995–1997. The predominant species was Escherichia coli, representing 68% of the isolates; others included Staphylococcus saprophyticus (8%), Group B streptococci (7%), Proteus spp. (6%), Klebsiella spp. (4%) and Enterococcus spp. (3%). More than 10% of the E. coli isolates were resistant to ampicillin, cephalothin, tetracycline and trimethoprim–sulfamethoxazole (TMP–SMX ) during both study periods, with the greatest increase in resistance to ampicillin and TMP/SMX between the two periods. Six hundred and four urinary tract infection isolates, including 83% E. coli, 7% S. saprophyticus, 3% Klebsiella spp. 2% Proteus spp., 2% enterococci, 1% Enterobacter spp. and 2% other organisms, were collected from women with acute cystitis attending a university student health service during 1995. Among E. coli isolates, 25% were resistant to ampicillin, 24% to tetracycline and 11% to TMP–SMX. Resistance to fluoroquinolones was essentially absent among gram-negative pathogens. Continued evaluation of susceptibility patterns of pathogens causing acute uncomplicated cystitis to traditional as well as new antimicrobials in well defined populations is necessary to ascertain the optimal empiric therapy.     

Evidence of a conjugal erythromycin resistance element in the Lyme disease spirochete Borrelia burgdorferi

We report the identification of isolates of Borrelia burgdorferi strain B31 that exhibit an unusual macrolide–lincosamide (ML) or macrolide–lincosamide–streptogramin A (MLS_A) antibiotic resistance pattern. Low-passage isolates were resistant to high levels (>100 μg/mL) of erythromycin, spiramycin and the lincosamides but were sensitive to dalfopristin, an analogue of streptogramin B. Interestingly, the high-passage erythromycin-resistant strain B31 was resistant to quinupristin, an analogue of streptogramin A (25 μg/mL). Biochemical analysis revealed that resistance was not due to antibiotic inactivation or energy-dependent efflux but was instead due to modification of ribosomes in these isolates. Interestingly, we were able to demonstrate high-frequency transfer of the resistance phenotype via conjugation from B. burgdorferi to Bacillus subtilis (10⁻²–10⁻⁴) or Enterococcus faecalis (10⁻⁵). An intergeneric conjugal system in B. burgdorferi suggests that horizontal gene transfer may play a role in its evolution and is a potential tool for developing new genetic systems to study the pathogenesis of Lyme disease.     

Macrolide-lincosamide-streptogramin B resistance phenotypes in clinical staphylococcal isolates

The prevalence of macrolide-lincosamide-streptogramin B (MLSB) resistance as well as the MLSB resistance phenotypes were investigated by the double-disk diffusion test among 532 clinical staphylococci isolates in a Turkish university hospital. The activity of other antimicrobials, including trimethoprim/sulfamethoxazole, telithromycin, quinupristin/dalfopristin, linezolid, gentamicin, chloramphenicol, ciprofloxacin and vancomycin, was also evaluated. Of 532 isolates, 38.5% were resistant to MLSB antibiotics; 63.9% of the resistant isolates exhibited a constitutive phenotype (cMLSB) whereas 36.1% expressed an inducible resistance phenotype (iMLSB). MLSB resistance was more prevalent among coagulase-negative staphylococci (CoNS) strains. Oxacillin-resistant strains exhibited significantly higher MLSB resistance rates compared with oxacillin-susceptible strains (P<0.0001). The most frequently detected resistance phenotype among the total staphylococcal isolates was the constitutive type and this phenotype was more frequently encountered among oxacillin-resistant strains. With the exception of the fully active agents such as vancomycin, linezolid and quinupristin/dalfopristin, the most effective antibiotics were telithromycin and chloramphenicol among all isolates. Susceptibility rates to other antibiotics tested were higher among isolates without MLS(B) resistance than isolates with MLSB resistance. The detection of a considerable rate (43.5%) of iMLSB resistance among erythromycin-resistant/clindamycin-susceptible strains suggests that the true percentage of clindamycin resistance may be underestimated if testing for inducible resistance is not performed.     

肠杆菌科细菌3年耐药性监测

目的了解我院2008年—2010年间临床常见肠杆菌科细菌的耐药情况及研究耐碳青霉烯类大肠埃希菌碳青霉烯酶基因型,为临床合理使用抗菌药物提供依据。方法收集我院2008-2010年间临床分离的常见肠杆菌科细菌,药敏试验使用纸片扩散法,数据分析采用WHONET5.4软件;筛选出对碳青霉烯类耐药的大肠埃希菌进行碳青霉烯酶基因的PCR检测及基因序列分析。结果 3年分离病原株共4916株,肠杆菌科共1980株,其中列前三位的是大肠埃希菌(873/1980),克雷伯菌属(605/1980)及肠杆菌属(268/1980),其次为变形菌属和沙雷菌属。主要来源于痰液、尿液及分泌物、血液、脓液等。重要肠杆菌科细菌对碳青霉烯类耐药率均小于10%,对头孢哌酮/舒巴坦、阿米卡星、哌拉西林/三唑巴坦者<30%,对广谱青霉素类及头孢菌素类者为40.9%～98.7%。变形菌属除对氨苄西林的耐药率>75%外,对其余抗生素的耐药率均低于40%,。3年来产超广谱β-内酰胺酶大肠埃希菌为33.97%及肺炎克雷伯菌57.50%,对大多数抗生素的耐药率显著高于非ELSBs菌株,且呈多重耐药。3年耐碳青霉烯类的大肠埃希菌共23株,其中产碳青霉烯酶者2株,PCR检测基因型阴性。结论本院肠杆菌科细菌大肠埃希菌和肺炎克雷伯菌检出率较高,碳青霉烯类对肠杆菌科细菌的抗菌活性最高,产ESBLs肠杆菌的耐药严重,实验室应加强对产ESBLs细菌的监测与报告。未检测出我院大肠埃希菌碳青霉烯酶基因型。治疗肠杆菌科细菌感染可选择碳青霉烯类,哌拉西林/三唑巴坦,头孢哌酮/舒巴坦,阿米卡星。     

Antimicrobial resistance of enterococci in Turkey

Susceptibility to ampicillin, penicillin, vancomycin and teicoplanin, high-level resistance to aminoglycosides (gentamicin and streptomycin) and β-lactamase production were investigated among 264 consecutive clinical enterococcal isolates in Turkey. Disc diffusion test was used to detect resistance to ampicillin, penicillin, vancomycin and teicoplanin. High-level resistance to aminoglycosides was determined both by standard agar screening and by disc diffusion methods. The values of minimum inhibitory concentration (MIC) of each isolate for ampicillin, vancomycin and teicoplanin were determined by the microbroth dilution technique. The isolates were found to consist of Enterococcus faecalis (78%), Enterococcus faecium (9%) and Enterococcus spp. (12%). In all strains, the penicillin and ampicillin resistance ratios were 27% and 26%, respectively. Enterococcus faecalis was more susceptible to penicillin and ampicillin than the other strains. None of the strains were resistant to glycopeptides. High-level aminoglycoside resistance was found in 16% E. faecalis and 88% E. faecium for gentamicin, and 35% and 44%, respectively, for streptomycin. There were no differences between the two methods used to determine the aminoglycoside resistance rates in the enterococcal isolates. No β-lactamase-producing isolates were detected in either species. In conclusion, to determine the resistance of enterococci to the penicillin group of drugs by the disc diffusion method, both penicillin and ampicillin discs should be evaluated. In serious enterococcal infections, before starting combined therapy, high-level aminoglycoside resistance should be investigated.     

鲍曼不动杆菌耐药表型与外排泵基因表达水平的研究

目的 探讨鲍曼不动杆菌临床分离株对常用抗菌药物的耐药性及与外排泵adeA基因表达水平之间的关系.方法 琼脂二倍稀释法检测鲍曼不动杆菌临床分离株对17种常用抗菌药物的最低抑菌浓度(MIC);PCR法扩增外排泵编码基因adeA:实时荧光定量RT-PCR(Real Time Fluorescent Quantitative RT-PCR)法检测adeA基因的mRNA表达水平.结果 药敏结果显示86株鲍曼不动杆菌对多粘菌素B全部敏感(100%),其次是美罗培南(73.2%)、亚胺培南(70.9%).耐药率最高的是庆大霉素(84.9%),其次为美罗西林(83.7%)和环丙沙星(79.1%).55株菌为多重耐药株(64%),其中5株(5/86)对多粘菌素B外的所有抗菌药物耐药(5.8%).adeA的检出阳性率为84.9%(73/86),Real Time RT-PCR结果显示多重耐药菌株adeA基因的mRNA相对表达量均高于敏感菌株,其中3株相对表达量为敏感菌株平均表达水平的30倍以上.结论 鲍曼不动杆菌临床分离株耐药情况严重,其主动外排系统adeA基因表达增强在多重耐药性形成中起重要作用.     

120株肠球菌耐药分析及药物选择

目的观察肠球菌属的临床分布特点及耐药状况。方法收集医院2011年1月～6月培养检出的120株肠球菌属,分析其在各种临床标本中的分布特征和耐药状况。结果检出粪肠球菌63株(52.5%)、屎肠球菌48株(40.8%)、其他肠球菌8株(6.7%)。其中尿液中检出58株肠球菌(48.3%)。屎肠球菌的耐药率普遍较粪肠球菌高。未检出耐万古霉素的尿肠球菌和粪肠球菌,检出耐利奈唑胺粪肠球菌2株。结论肠球菌属感染以粪肠球菌和屎肠球菌为主,肠球菌属中各种菌对抗菌药物的耐药性有差异,应在抗菌药物敏感试验指导下并结合感染部位合理地选用抗菌药物。     

2017年安徽省某三甲医院细菌耐药性监测

目的 了解铜陵市人民医院2017年临床分离细菌对抗菌药物的耐药状况。方法 对2017年1-12月临床分离菌采用纸片扩散法(KB)进行药敏试验，按CLSI 2017年版标准判读药敏试验结果，采用WHONET 5.6软件进行数据分析。结果 临床分离细菌共3436株，其中革兰阳性菌719株，占20.9%；革兰阴性菌2717株，占79.1%。耐甲氧西林金黄色葡萄球菌(MRSA)和耐甲氧西林凝固酶阴性葡萄球菌(MRCNS)的检出率分别为23.8%和72.3%，耐甲氧西林株对β-内酰胺类抗生素和其他测试抗菌药物的耐药率显著高于甲氧西林敏感株，未发现对万古霉素和替考拉宁耐药的葡萄球菌。粪肠球菌对青霉素、氨苄西林和呋喃妥因的耐药率较低，屎肠球菌对氯霉素的耐药率较低，5.3%屎肠球菌对万古霉素耐药。大肠埃希菌、克雷伯菌属(肺炎克雷伯菌和产酸克雷伯菌)和奇异变形菌中ESBLs的检出率分别为41.4%、50.7%和19.4%。肠杆菌科细菌中克雷伯菌属和沙雷菌属对碳青霉烯类抗生素耐药率较高，分别为37.5%和36.0%，其他菌属的耐药率低于3%。鲍曼不动杆菌对亚胺培南和美罗培南的耐药率分别80.3%和79.1%；铜绿假单胞菌对亚胺培南和美罗培南的耐药率分别为29.7%和28.4%。肺炎克雷伯菌、鲍曼不动杆菌和铜绿假单胞菌中广泛耐药株的检出率分别为31.3%(171/546)、0.6%(3/508)和0.7%(3/416)。结论 本院革兰阴性菌呈增多趋势，尤其广泛耐药的肺炎克雷伯菌应引起高度关注，做好细菌耐药性监测，加强临床抗菌药物的合理使用和医院感染控制。     

Molecular epidemiology and antibiotic resistance of Enterobacter spp. from three distinct populations in Grampian,UK

The distribution of Enterobacter spp. within the population of Aberdeen Royal Infirmary was compared with the outpatient population with regard to molecular epidemiology and antibiotic resistance. Enterobacter spp. from 60 patients and one environmental site were characterised as ITU, non ITU and outpatients’ isolates. Thirty-five percent were blood culture isolates. Cefotaxime resistant strains in the hospital were frequent. Cefotaxime (64%) sensitive isolates were inducible for hyperproduction of Bush group 1 β-lactamase. Isolates were further investigated by PFGE. Isolates (27%) were clonally related and typed in four clusters. Consecutive isolates were studied in selected patients showing minor genomic changes. One environmental isolate from a deep sink at ITU was related to a patient's isolate.     

2002年临床常见革兰氏阴性杆菌耐药性监测

目的　调查国家细菌耐药性监测网临床常见革兰氏阴性杆菌对各种抗菌药物的耐药性现状。方法　药物敏感性试验采用纸片扩散法 ,耐药性数据分析采用 WHONET5软件。结果　 2 0 0 2年国家细菌耐药性监测网 8个省、市、自治区的 5 7家三级甲等医院共收集患者首次分离株 2 4 82 6株 ;大肠埃希氏菌、铜绿假单胞菌和肺炎克雷伯氏菌是最常见菌。主要标本为痰、尿和伤口及分泌物 ,分别占全部标本的 4 7.9% ,16 .8%和 10 .4 %。绝大多数肠杆菌科细菌对亚胺培南和美罗培南敏感 ,其次为第三代头孢菌素、含酶抑制剂的头孢菌素及阿米卡星。 15 % (15 .6 %～ 5 1.2 % )的肠杆菌、柠檬酸杆菌、沙雷氏菌和普罗威登氏菌对第三代头孢菌素耐药。除大肠埃希氏菌外 ,环丙沙星和左氧氟沙星对其他肠杆菌科细菌的耐药率低于 30 % (6 .0 %～ 2 9.7% ) ;产超广谱β-内酰胺酶 (ESBL s)的大肠埃希氏菌和肺炎克雷伯氏菌株的检出率分别为 18.2 %和 2 2 .6 % ;铜绿假单胞菌对亚胺培南和美罗培南的耐药率分别为 19.1%和 15 .2 %。鲍氏不动杆菌对碳青霉烯类抗生素较敏感 ,但对头孢哌酮、头孢他啶和阿米卡星的耐药率分别为 5 2 .8% ,4 1.6 %和 31.8%。结论　细菌耐药性问题是抗感染治疗的主要威胁 ,合理使用抗菌药物以降低耐药性和采取有效措     

Susceptibility patterns of Enterococcus spp. isolated in Poland during 1996

Susceptibility of Enterococcus spp. isolated from various clinical specimens to different antimicrobial agents was evaluated. Of the 346 enterococcal isolates obtained from four regional Polish hospitals during 6 months of 1996, 261 (75.4%) were identified as Enterococcus faecalis, 75 (21.7%) as Enterococcus faecium and ten (2.9%) as other enterococcal species. High-level resistance to gentamicin was expressed by 33.4% of E. faecalis and 86.5% of E. faecium strains and corresponding streptomycin resistance by 43.9 and 82.4%, respectively. Over 80% of E. faecium isolates were resistant to ampicillin. None of the isolates was resistant to teicoplanin, however 7.9% of E. faecalis and 1.4% of E. faecium strains were moderately susceptible to vancomycin.     

Examination of cfiA-mediated carbapenem resistance in Bacteroides fragilis strains from a European antibiotic susceptibility survey

Of 1284 Bacteroides strains collected in Europe in 2000 for antibiotic susceptibility surveillance, 65 isolates displayed imipenem minimum inhibitory concentrations (MICs) ≥1 mg/L and were chosen for a thorough analysis of their resistance mechanism. Twenty-five of the isolates were positive for the cfiA carbapenem resistance gene. The resistance rates were 0.8% and 1.3% for imipenem and meropenem, respectively. In six of the strains, insertion sequence (IS) elements (IS613, IS614B, IS1186 and IS1187) activated the cfiA gene. However, other strains displayed at least elevated carbapenem MICs or were carbapenem resistant and produced measurable carbapenemase activities but did not harbour IS elements in the region upstream of the cfiA gene. The major determinant of carbapenem resistance in Bacteroides fragilis is production of CfiA metallo-β-lactamase via activation of the cfiA gene by IS elements (higher level resistance) or by activation of its putative own promoter.